Flash Flood in Waukesha County, Wisconsin

Heavy rains resulted in flash flooding across much of Waukesha County. Water reached depths of 3 feet or more and several cars stalled. This was one of 4 flash floods in Waukesha County that occurred on Junen 7th and 8th. Collectively, each of these 4 flash floods resulted in home and business damage along with some crop losses. It was nearly impossible to break down the damages by flash flood event. Therefore, the collective breakdown for all of Waukesha County is provided in this flash flood event.

The breakdown for residential home losses were: 1433 with minor damage, 188 with major damage, and 1 destroyed (total of $54.632 million for home losses). Business losses totaled $5.462 million. Crop losses were estimated at $1 million. Public sector damage wa

s about $2.9 million. There were several roads and bridges that sustained damage.

A slow-moving surface boundary, nearly parallel with the mid-level flow affected southern Wisconsin during the period of June 7th through June 9th. A strengthening low-level jet and strong moisture advection produced several rounds of thunderstorms during the period in the vicinity of this boundary. The atmosphere was very moist with precipitable water values around 2 inches. Low to mid-level wind flow supported training of flood-producing thunderstorms. A weak cool front pushed through southern Wisconsin late on the 8th/early on the 9th, finally ending the heavy rainfall.

The heavy rain axis for June 7-9th ran from Sauk County southeast to Milwaukee County, where generally 6 to 9 inches fell on a ground that was totally saturated due to record-setting winter snowfalls and a wet April, 2008. Several locations topped 10 inches, and Watertown (Jefferson Co.) came in with 13.5 inches, 11.35 inches was measured in Oak Creek (Milwaukee Co.), and Elm Grove in Waukesha County picked up 10.8 inches.